1. Field of the Invention
The present invention relates generally to the field of video processing and, more specifically, to video retargeting using content-dependent scaling vectors.
2. Description of the Related Art
Presently, display systems for video content present a variety of different formats. Where a video format includes video stream characteristics such as the video's image resolution (image width and image height in pixels) and the video's image aspect ratio (image width divided by the image height). However, the original video content is typically produced in a single format. Certain video formats targeted for television broadcast or cinematic presentation are fairly standardized. However, the proliferation of handheld devices such as tablet computers and mobile phones has resulted in display systems with display formats that are significantly different from the original video formats.
In order for video produced in one format to be displayed on a device with a different display format, the video is retargeted from the original video format to the target device's display format. Specifically, with regards to the video image resolution, such retargeting is accomplished through linear scaling or letter-boxing. With linear scaling, the original video image is linearly scaled in the horizontal and vertical dimensions to fit the target display resolution. With such an approach, the horizontal scaling is performed separately from the vertical scaling. Where the aspect ratio of the original video is significantly different from the target aspect ratio of the display device, linear scaling distorts the original video, causing a perceptually unpleasant viewing experience. With letter-boxing, the original video image is proportionally scaled to preserve the original aspect ratio of the original video image on the target display device. Black bars are presented on the top and bottom or on the left and right of the display device to account for the difference in resolution between the target display resolution and the retargeted image resolution. However, when using letter-boxing, the maximum usable area of the display is not utilized, which is particularly problematic for smaller display devices.